ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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PolypodiacesB they are more robust ; while in the Osmundaceae, except 
Todea, and in the Marattiaceae, they are thick and almost coriaceous, 
developing, in some genera, as the massive “ stipules.” 
The sporanges, in their mode of origin and structure, give evidence 
of a similar series ascending in complexity and consisting of the 
Hymenophyllaceae, Polypodiaceae, SchizaBaceae, Osmundaceae, and Marat- 
tiaceae. The change in form of the archespore, from conical in the 
leptosporangiate ferns to cubical in the eusporangiate, is similar to that 
of the initial cells of the root, stem, leaf, and wing. The structure of 
the wall and the tapete is more complex in the eusporangiate ferns, and 
the number of spores in each sporange is larger, while the sporanges 
themselves are fewer in number. 
Tissues of the Leaves of Ferns.* — Herr A. Vinge classifies ferns 
under three heads in relation to the structure of the tissue of their 
leaves, viz. : — (1) All the mesophyll-cells are fiat, i. e. the vertical is 
less than the longitudinal or lateral diameter, even in the cells of the 
uppermost chlorophyllous layer ; (2) the cells of the uppermost chloro- 
phyllous layer of the mesophyll are usually nearly isodiametrical ; 
('3) a typical palisade-parenchyme occurs on the upper side of the leaf. 
Several subdivisions are described in each class, and a large number of 
species named belonging to each subdivision. 
Underground Development and Affinities of Sigillaria.t — M. Grand’ 
Eury shows, by characters drawn from the development, together with 
those of reproduction, that the Sigillarise are Cryptogams of a high 
degree of organization. The stem is characterized by presenting itself 
at first in the form of large undifferentiated tubers; and it is only 
gradually that the root assumes the character of Stigmaria. The author 
concludes by stating that the Sigillarise belong to no living type of 
Cryptogams, and that they form a family of fossil plants which entirely 
disappeared at the end of the palseozoic epoch. 
Leaves of Lepidodendron.J — M. B. Eenault describes the leaves 
attached to the branches of Lepidodendron rliodunnense, reserving for a 
later description those belonging to L. esnostense. The leaves of 
L. rhodunnense are small and short and 5-6 cm. long at the base, 
measuring 3 mm. and 1 • 5 in thickness. Their transverse section some- 
what recalls the leaves of Sigillaria. The axis of the leaf is occupied 
by a single vascular bundle composed of radiating tracheids. The 
bundle is completely surrounded by a layer of parenchymatous cells, 
which constitute the liber ; this liber is itself surrounded by a layer of 
thick sclerenchymatous cells. The leaves of L. rhodunnense differ from 
those of Sigillaria on the outside by the absence of the furrow on the upper 
surface of the leaf towards the base. When it exists in the middle 
region of the leaf it is less marked than in Sigillaria. The peculiar 
vasiform tissue which is common to these two genera of fossil plants was 
intended, no doubt, to ward off any inconvenient results caused by the 
alternating humidity and excessive dryness to which the plants of this 
epoch were exposed. 
* Lunds Univ. Arsskr., xxv. (1889) 82 pp. and 3 pis. See Hedwigia, xxviii 
(1889) p. 290. 
t Coniptes Rendus, cviii. (1889) pp. 879-83. J Op. o., cix. (1889) pp. 41-3. 
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